Skeletal Muscle Anatomy and Function Quiz

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Questions and Answers

What is the primary function of the phosphagen system?

To break down glucose into pyruvate

To provide immediate ATP using creatine phosphate (correct)

To convert fatty acids into energy

To utilize oxygen for energy production

Which of the following correctly describes the duration of ATP production via the phosphagen system?

Up to 30 seconds of sustained energy

Only for aerobic exercise lasting more than 5 minutes

Continuous energy supply lasting over 5 minutes

A maximum of 3-15 seconds of immediate energy (correct)

What type of exercise primarily utilizes the anaerobic glycolysis system?

Low-impact aerobic exercises focusing on endurance

Long-distance running with high oxygen demand

High-intensity, short-duration power activities (correct)

Continuous moderate lifting with low rest

Which substrate is converted into pyruvate during glycolysis?

Glucose Signup and view all the answers

Which statement about oxygen usage in energy systems is true?

Anaerobic glycolysis can function without oxygen Signup and view all the answers

What is the primary function of the actin filament in a sarcomere?

Sliding over myosin during contraction Signup and view all the answers

What is the role of troponin in muscle contraction?

Regulating the interaction between actin and myosin Signup and view all the answers

During which phase is a muscle the strongest?

In the middle of its range of motion Signup and view all the answers

Which statement correctly describes the mechanism of an eccentric contraction?

Involves slow relaxation of myosin heads Signup and view all the answers

What is the significance of the Z band in a sarcomere?

It defines the boundaries of the sarcomere Signup and view all the answers

How many actin filaments surround each myosin filament in a sarcomere?

6 actin filaments Signup and view all the answers

What role does titin play in the muscle fiber?

Providing resistance and elasticity to stretch Signup and view all the answers

What structural component is known as a fascicle in skeletal muscle?

A bundle of muscle fibers Signup and view all the answers

What state are the Na+ gates in during the resting membrane potential?

Closed Signup and view all the answers

What initiates an action potential after a stimulus is received?

Dendrites or soma Signup and view all the answers

During the depolarization phase, what is the state of the K+ gates?

Closed Signup and view all the answers

What happens to the Na+ gates during the repolarization phase?

They are inactivated Signup and view all the answers

What ion movement occurs during hyperpolarization?

K+ out Signup and view all the answers

What principle outlines that an action potential can only occur at a certain amplitude?

All or none principle Signup and view all the answers

What is the function of the absolute refractory period during repolarization?

To prevent backwards propagation of action potentials Signup and view all the answers

What describes the structural nature of myelin?

Lipid Signup and view all the answers

What phase of muscle contraction is represented when a weight is raised during a bench press?

Concentric phase Signup and view all the answers

Where are the cell bodies of alpha motor neurons located in the body?

In the spinal cord Signup and view all the answers

Which neurotransmitter is primarily responsible for synaptic transmission at the neuromuscular junction?

Acetylcholine Signup and view all the answers

What is the term for the maximum amount of weight that can be raised in a concentric phase?

One-repetition maximum Signup and view all the answers

What is the role of action potentials in muscle contraction?

They facilitate communication between the brain and muscles. Signup and view all the answers

Which contraction phase occurs when a weight is being lowered during a bench press?

Eccentric phase Signup and view all the answers

What physiological process occurs when neurotransmitters bind to the muscle cell membrane?

Calcium ion release from the sarcoplasmic reticulum Signup and view all the answers

What does a 1-repetition maximum test primarily measure?

Maximal strength output Signup and view all the answers

Which of the following correctly describes the P-R interval in the cardiac cycle?

The time it takes for electrical activity to travel from the atria to the ventricles. Signup and view all the answers

In Wigger’s Diagram, what does the aortic valve closing signify?

The end of ventricular filling. Signup and view all the answers

Which cardiac arrhythmia is characterized by an irregular, often rapid heart rate due to chaotic electrical signals in the atria?

Atrial Fibrillation Signup and view all the answers

What is the electrical event represented by the QRS complex in an electrocardiogram?

Ventricular depolarization Signup and view all the answers

What is the term for a heart rate that is faster than normal, opposite to bradycardia?

Tachycardia Signup and view all the answers

What is the total number of ATP produced from 10 NADH molecules during cellular respiration?

25 ATP Signup and view all the answers

How many NADH are produced from one complete turn of the Krebs cycle?

3 NADH Signup and view all the answers

What is the correct stoichiometry for the creation of water in the electron transport chain?

2H + ½ O + 2e- → H2O Signup and view all the answers

From pyruvate to acetyl Co-A, how many NADH molecules are generated?

2 NADH Signup and view all the answers

How many turns of the Krebs cycle occur for each molecule of glucose metabolized?

2 turns Signup and view all the answers

How much ATP is produced from one FADH2 during the electron transport chain?

1.5 ATP Signup and view all the answers

Which hormone is primarily responsible for regulating blood glucose levels?

Glucagon Signup and view all the answers

What is the actual total ATP production for one glucose molecule after glycolysis, the Krebs cycle, and the electron transport chain?

32 ATP Signup and view all the answers

During glycolysis, how many ATP are used initially to convert glucose to pyruvate?

2 ATP Signup and view all the answers

What is the primary function of catecholamines?

Promoting stress response Signup and view all the answers

Which pair of hormones is involved in the regulation of stress and metabolism?

Epinephrine and norepinephrine Signup and view all the answers

Which hormone primarily contributes to the development of male secondary sexual characteristics?

Testosterone Signup and view all the answers

Which hormone is secreted in response to low blood glucose levels?

Glucagon Signup and view all the answers

What is the primary role of growth hormone in the body?

Promoting muscle growth and development Signup and view all the answers

Which hormone is primarily involved in maintaining fluid balance in the body?

Aldosterone Signup and view all the answers

Which of the following is a primary function of epinephrine?

Preparing the body for 'fight or flight' Signup and view all the answers

Which of these hormones plays a role in both metabolism and the stress response?

Cortisol Signup and view all the answers

Which pair of hormones is commonly associated with the body's response to stress?

Epinephrine and norepinephrine Signup and view all the answers

What hormone is primarily responsible for increased sodium reabsorption and water retention during exercise?

Aldosterone Signup and view all the answers

Which physiological response occurs when blood volume decreases due to fluid loss from exercise?

Increased Renin release Signup and view all the answers

What is the effect of angiotensin II following blood volume loss?

Increased aldosterone release Signup and view all the answers

Under what condition is erythropoietin released from the kidneys?

Hypoxia Signup and view all the answers

What is the primary effect of aldosterone on kidney function?

Increases potassium excretion Signup and view all the answers

How does exercise influence blood pressure via hormonal responses?

Increased production of angiotensin II Signup and view all the answers

Which of the following mechanisms contributes to increased heart rate during exercise?

Increased sympathetic nervous system activity Signup and view all the answers

What immediate effect does prolonged exercise have on blood composition?

Increased blood concentration Signup and view all the answers

What does increased ADH release primarily promote in response to exercise?

Increased water absorption Signup and view all the answers

Which of the following statements about the effects of exercise on the cardiovascular system is true?

Exercise enhances the release of aldosterone. Signup and view all the answers

What causes air to leave the lungs during expiration?

Reduction in lung volume Signup and view all the answers

What is the relationship between lung pressure and lung volume during expiration?

Lung pressure increases while lung volume decreases Signup and view all the answers

How does pressure in the pleural space relate to lung pressure during a typical breath cycle?

Pleural space pressure decreases as lung volume increases Signup and view all the answers

What occurs at the end of expiration in terms of pressure and lung volume?

Lung volume is decreasing while pressure equalizes to 760 mmHg Signup and view all the answers

What effect does diaphragm relaxation have on lung dynamics during expiration?

It leads to a decrease in lung volume and an increase in lung pressure Signup and view all the answers

Which structure is responsible for the delivery of deoxygenated blood from the body back to the heart?

Inferior vena cava Signup and view all the answers

What is the correct pathway of blood flow starting from the lungs?

Lungs → left atrium → left ventricle → aorta → arteries Signup and view all the answers

What does an electrocardiogram (ECG) primarily measure?

Electrical activity of the heart Signup and view all the answers

Which heart valve separates the left atrium from the left ventricle?

Bicuspid (mitral) valve Signup and view all the answers

Which component is NOT part of the cardiovascular pathway of blood?

Neurons Signup and view all the answers

Which of the following structures includes the valves that prevent backflow of blood in the heart?

Chambers of the heart Signup and view all the answers

What is the function of pulmonary arteries in the circulatory system?

Carry deoxygenated blood to the lungs Signup and view all the answers

What does the QRS complex in an ECG represent?

Ventricular depolarization Signup and view all the answers

Which of the following best describes the role of the aortic valve?

Allows oxygenated blood to flow into the aorta Signup and view all the answers

Where is the electrical activity recorded in an electrocardiogram generated?

Sinoatrial node Signup and view all the answers

Study Notes

Skeletal Muscle Anatomy and Function

Skeletal muscle consists of fascicles, also known as bundles of muscle fibers (cells).
Key components of muscle fiber: myofibrils and sarcomeres, which are the basic contractile units.
Sarcomeres contain actin and myosin filaments, responsible for muscle contraction.
The Z band defines the boundaries of each sarcomere.

Sarcomere Function

Actin filaments slide during muscle contraction, aided by the mechanism of muscle proteins.
Eccentric contractions involve slow relaxation of myosin heads and stretching of connective tissue forces.
Each myosin has several actin filaments surrounding it, which enhances the interaction during contraction.

Muscle Strength Dynamics

Muscles exhibit maximum strength in mid-range positions during contractions.
Muscles are weakest when at extreme positions with no overlap of actin and myosin.

Range of Motion in Muscle Contraction

Different phases of contraction include concentric (muscle shortening), isometric (muscle length stays constant), and eccentric (muscle lengthening).
A 1-repetition maximum is defined as the heaviest weight that can be lifted in a single effort through a full range of motion.

Alpha Motor Neurons

Cell bodies of motor neurons are located in the spinal cord.
Action potentials facilitate communication between the brain and muscles, traveling along axons.

Synaptic Transmission

Acetylcholine (Ach) is the neurotransmitter at the neuromuscular junction (NMJ).
Binding of Ach to muscle membrane triggers depolarization, beginning an action potential in the muscle cell.

Action Potential Phases

Resting Membrane Potential: Sodium (Na+) gates are closed; potassium (K+) gates also remain closed.
Depolarization: Na+ gates open, allowing Na+ to flow into cells.
Repolarization: Na+ gates inactivate, K+ gates open, allowing K+ to exit cells.
Hyperpolarization: Na+ gates remain inactive; K+ gates open; ion movement stops after initial outflow.

All or None Principle

The action potential exhibits an all-or-none response, with amplitude remaining constant.
Variation in stimulus strength is achieved through the frequency of action potentials.

Energy Transfer Systems

Three main energy systems:
- ATP-CP System: Provides immediate ATP via creatine phosphate, lasting 3-15 seconds without oxygen.
- Glycolysis: Converts glucose to pyruvate, playing a crucial role in both anaerobic and aerobic energy production.

Cardiac Physiology

Wigger’s Diagram depicts cardiac cycle events including atrial depolarization (P wave) and ventricular depolarization (QRS complex).
Cardiac arrhythmias can manifest as bradycardia, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation.
Bradycardia refers to abnormally slow heart rate, while tachycardia denotes an excessively fast pulse.

Practical Example: Exercise Dynamics

Bench press showcases concentric, isometric, and eccentric contractions in a full range of motion.

Cellular Respiration Overview

NAD+ is reduced to NADH during metabolic processes.
Water is formed at the end of the Electron Transport Chain (ETC) through the reaction 2H + ½ O + 2e- → H2O.

Glycolysis

Converts glucose to pyruvate.
ATP consumption: 2 ATP.
ATP production: 4 ATP (net gain: 2 ATP).
NADH produced: 2 NADH.

Pyruvate to Acetyl CoA

Produces 2 NADH.

Krebs Cycle (Citric Acid Cycle)

Each cycle produces:
- 3 NADH
- 1 FADH2
- 1 ATP
Each glucose undergoes 2 turns of the Krebs Cycle.

Electron Transport Chain Efficiency

Each NADH yields approximately 2.5 ATP.
Each FADH2 yields approximately 1.5 ATP.

Total ATP Production Calculation

From 10 NADH: 2.5 x 10 = 25 ATP.
From glycolysis: 2 ATP.
From Pyruvate to Acetyl CoA: 2 NADH = 2 ATP.
From Krebs cycle: 6 NADH = 15 ATP; 2 FADH2 = 3 ATP; total from Krebs cycle = 20 ATP.
Overall, total ATP = 32 ATP.

Metabolism of Fat and Protein

Enhanced water absorption and blood pressure during metabolism alters renal function.
Increases Na+ reabsorption, causing potassium excretion, elevated heart rate, sympathetic nervous system activity, and aldosterone levels.

Water Retention Mechanism

Exercise-induced fluid loss concentrates blood, reducing blood volume.
Response includes:
- Increased ADH and renin release, leading to angiotensin II production.
- Angiotensin II causes vasoconstriction and increases aldosterone and ADH release, aiding water retention.

Erythropoietin Function

Released from kidneys in response to low red blood cell count or hypoxia.
Stimulates the production of red blood cells.

Catecholamines Role

Involve neurotransmitters like epinephrine and norepinephrine, affecting various physiological responses.

Heart Anatomy and Blood Flow Pathway

Know the chambers and valves of the heart.
Blood flow pathway: Lungs → left atrium → left ventricle → aorta → arteries → arterioles → capillaries → venules → veins → vena cava → right atrium → right ventricle → lungs.

Electrocardiograph (ECG or EKG)

Measures electrical activity of the heart.
Records changes reflecting heart rhythm and potential abnormalities.

Respiratory Mechanics

During expiration, pleural pressure changes inducing air to leave the lungs.
Pressure in the pleural space decreases while lung volume increases and intrapleural pressure rises.

Summary of Pressure Changes

At rest, pleural pressure and lung volume are balanced at 760 mmHg.

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Description

Test your knowledge on the anatomy and function of skeletal muscle with this quiz. Explore concepts including muscle fiber structure, sarcomere dynamics, and muscle strength during contractions. Perfect for students studying human anatomy or physiology.